Peters



UNITED STATES PATENT OFFICE.

EDWIN MAY, OF INDIANAPOLIS, INDIANA.

WINDOW-GRATING- FOR PRISONS.

Specicaton of Letters Patent No. 28,496, dated May 29, 1860.

To all whom it may concern:

Be it known that I, EDWIN MAY, of Indianapolis, in the county of Marion, in the State of Indiana, have invented a new and Improved Method of Making Saw-Proof Grrating for Prisons; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings and to the letters of reference marked thereon.

The nature of my invention consists in making gratings for prisons, saw or file proof.

To enable others to make and use my invention I will proceed to describe its construction and operation.

I construct my bars of wrought iron tubes or pipes, and in the forms as shown by the accompanying drawings. After I have formed the tubing into the proper curves for the grating as shown at Figures l, 2, 3 and 4, I fill the tubing with cast iron, which be comes chilled by being surrounded with the cold wrought iron tubing so that a saw or le will not cut through the bars or grating and the two metals combined in the form as shown by the drawings will make a inuch stronger grating than in the usual manner.

In making the grating as shown at Figs. 5, 6, 7 and 8, I bolt the wrought iron tubes F and G together with the bolt H, Fig. 8. The

whole is then filled with cast iron which ef fectually surrounds the bolt H making the bolt act as a double rivet and securely fastens the tube F and G together. The head of the bolt H may be cut olf on the outside and the bars F and Gr will remain securely bolted together.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent isl. The platting of tubular iron-the tubes crossing each other at right-angles substantially as, and for the purposes herein set forth.

2. The bolting together of right angle tubes, with the dove-tail bolt (II,) when the same is done for the purposes set forth.

3. Although I disclaim any originality in the filling of wrought iron tubes with molten iron, (that having been done before,) yet, after having platted the tubes, and riveted them as shown, I claim the lling of said tubes with molten iron-in combination with the dove-tail rivet (HQ- when all these parts, and ingredients, are used for the purposes described in the foregoing specifica- 

